The Brilliant Healer's New Life in the Shadows: Volume 4 (Light Novel) — Sakaku Hishikawa

The situation with Liz has been resolved, so Zenos shifts his focus to researching the Black Guild, a mysterious organization that closely guards all information about their members. Even so, he learns of an important figure within it who can supposedly heal any malady. Could it be his childhood friend and fellow student of healing magic, Velitra? Upon looking further into the matter, he suspects Velitra also has their old mentor’s notes. Finding his old friend could be the key to learning more about their mysterious mentor...Will Zenos manage to infiltrate the Black Guild? And if he does, what secrets will he unveil?